Methods for correction of spinal deformities

Abstract

A method of treating a spinal column shape deformation includes fixing at least two fixation screw assemblies to respective vertebrae, sliding a rod between the arm extensions on each of the fixation screw assemblies, swinging the channels of the screw assemblies relative to the fixation screws so that the channels become less inclined to the axes of the fixation screws, and so that the rod is located generally posteriorly of the spinal column, locking the channel against swinging relative to the screw, rotating the rod about its axis relative to at least one of the channels, and locking the rod against movement relative to the channel.

The invention claimed is: 
     
       1. A method for treating spinal column shape deformation comprising:
 fixing a first fixation screw assembly to a first vertebra of a patient's spinal column, the first fixation screw assembly having a fixation screw, a rod receiving channel with separable channel arm extensions, the channel being movable relative to the fixation screw through a range of angles, the first fixation screw assembly having a locking device for separately locking the channel against movement relative to the fixation screw and a rod against movement in the channel, 
 moving the channel relative to the fixation screw laterally relative to the spinal column toward the coronal plane of the spinal column to a first plane, 
 positioning a rod between the arm extensions and in the first plane, 
 moving the channel relative to the fixation screw medially relative to the spinal column toward the sagittal plane of the spinal column to place the rod in a second plane generally aligned with the sagittal plane, 
 adjusting the locking device along the arm extensions to move the rod within the channel, 
 adjusting the locking device to lock the channel relative to the fixation screw, 
 further adjusting the rod relative to the channel, and 
 adjusting the locking device to lock the rod against movement relative to the channel. 
 
     
     
       2. The method of  claim 1 , further comprising separating the arm extensions from the first fixation screw assembly. 
     
     
       3. The method of  claim 1 , wherein the channel of the first fixation screw assembly comprises a pair of approximately parallel spaced-apart channel arms and a base extending between the channel arms, one of the channel arm extensions provided on each of the channel arms and configured to be readily detachable from the arm. 
     
     
       4. The method of  claim 3 , wherein the locking device comprises a first locking member and a second locking member,
 wherein adjusting the locking device to lock the channel relative to the fixation screw comprises rotating the first locking member relative to the channel arms and causing the first locking member to act against the fixation screw directly or indirectly, and 
 adjusting the locking device to lock the rod against movement relative to the channel comprises rotating the second locking member relative to the first locking member and causing the second locking member to act against the rod directly or indirectly. 
 
     
     
       5. The method of  claim 4 , wherein the first locking member is a screw having an external thread for engaging a thread on internal faces of the arms, the first locking member having a threaded bore, and wherein the second locking member is a screw having an external thread for engaging the threaded bore of the first locking member. 
     
     
       6. The method of  claim 3 , wherein each of the arm extensions is connected to one of the channel arms at a line of weakness which promotes separation of the arm extension from its channel arm. 
     
     
       7. The method of  claim 6 , wherein a ratio of a length of one of the arm extensions measured from the line of weakness to a length of the channel arm measured from a base of the channel to the line of weakness is not more than about 1.0. 
     
     
       8. The method of  claim 1 , wherein adjusting the rod relative to the channel comprises rotating the rod about its axis relative to the channel. 
     
     
       9. The method of  claim 1 , wherein positioning the rod between the arm extensions includes sliding the rod in the coronal plane. 
     
     
       10. A method for treating spinal column shape deformation comprising:
 fixing a first fixation screw assembly to a first vertebra of a patient's spinal column and a second fixation screw assembly to a second vertebra of the patient's spinal column, the first fixation screw assembly and the second fixation screw assembly each having a fixation screw, a rod receiving channel, and a locking device, the rod receiving channel defined by two spaced apart channel arms, a base extending between the channel arms, and a separable channel arm extension provided on each of the channel arms, the channel of each screw assembly being movable relative to its fixation screw through a range of angles, the locking device of each screw assembly permitting separate locking of its channel against movement relative to its fixation screw and a rod against movement in its channel, 
 moving the channel of the first fixation screw assembly relative to its fixation screw laterally relative to the spinal column toward the coronal plane of the spinal column to a first plane, 
 moving the channel of the second fixation screw assembly relative to its fixation screw laterally relative to the s final column toward the coronal plane of the spinal column to a second plane, 
 positioning a rod between the channel arms or the channel arm extensions of the first fixation screw assembly and between the channel arms or the channel arm extensions of the second fixation screw assembly such that a portion of the rod lies in the first plane and a portion of the rod lies in the second plane, 
 moving the channel of the first fixation screw assembly relative to its fixation screw medially relative to the spinal column toward the sagittal plane of the spinal column to place a portion of the rod in a third plane generally aligned with the sagittal plane, 
 moving the channel of the second fixation screw assembly relative to its fixation screw medially relative to the spinal column toward the sagittal plane of the spinal column to place another portion of the rod in the third plane, 
 adjusting the locking device along the channel arm extensions of the first fixation screw assembly to move the rod within the channel toward the base of the first fixation screw assembly, 
 adjusting the locking device along the channel arm extensions of the second fixation screw assembly to move the rod within the channel toward the base of the second fixation screw assembly, 
 adjusting the locking device of the first fixation screw assembly relative to the channel arms of the first fixation screw assembly to lock the channel of the first fixation screw assembly relative to its fixation screw, 
 adjusting the locking device of the second fixation screw assembly relative to the channel arms of the second fixation screw assembly to lock the channel of the second fixation screw assembly relative to its fixation screw, 
 further adjusting the locking devices to move the rod within the channels of the first and second fixation screw assembly toward the bases of the first and second fixation screw assembly, 
 adjusting the locking device of the first fixation screw assembly to lock the rod against movement relative to the channel of the first fixation screw assembly, and 
 adjusting the locking device of the second fixation screw assembly to lock the rod against movement relative to the channel of the second fixation screw assembly. 
 
     
     
       11. The method of  claim 10 , further comprising separating the channel arm extensions from the channel arms of the first fixation screw assembly and separating the channel arm extensions from the arms of the second fixation screw assembly. 
     
     
       12. The method of  claim 11 , wherein the locking device of the first fixation screw assembly and the second fixation screw assembly each comprises a first locking member and a second locking member,
 wherein adjusting the locking device of the first fixation screw assembly to lock the channel of the first fixation screw assembly relative to its fixation screw comprises rotating the first locking member relative to the channel arms and causing the first locking member to act against its fixation screw directly or indirectly, and 
 adjusting the locking device of the first fixation screw assembly to lock the rod against movement relative to the channel of the first fixation screw assembly comprises rotating the second locking member relative to the first locking member and causing the second locking member to act against the rod directly or indirectly. 
 
     
     
       13. The method of  claim 12 , wherein the first locking member of the locking devices of the first and second fixation screw assemblies is a screw having an external thread for engaging a thread on internal faces of the channel arms, the first locking member having a threaded bore, and wherein the second locking member of the locking devices of the first and second fixation screw assemblies is a screw having an external thread for engaging the threaded bore of the first locking member. 
     
     
       14. The method of  claim 10 , wherein adjusting the rod relative to the channels of the first and second fixation screw assemblies comprises rotating the rod about its axis relative to the channels. 
     
     
       15. The method of  claim 10 , wherein positioning a rod between the arms or the arm extensions of the first fixation screw assembly and between the arms or the arm extensions of the second fixation screw assembly includes sliding the rod in the coronal plane. 
     
     
       16. The method of  claim 10 , wherein each of the channel arm extensions is connected to one of the channel arms of the first fixation screw assembly and the second fixation screw assembly at a line of weakness which promotes separation of the arm extension from its arm. 
     
     
       17. The method of  claim 16 , wherein a ratio of a length of a channel arm extension measured from the line of weakness to a length of the channel arm measured from a base of the channel to the line of weakness is not more than about 1.0. 
     
     
       18. A method for treating spinal column shape deformation comprising:
 fixing a fixation screw assembly to a vertebra of a patient's spinal column, the fixation screw assembly having a fixation screw, a rod receiving channel, and a locking device, the rod receiving channel defined by two spaced apart channel arms, a base extending between the arms, and a separable channel arm extension provided on each of the arms, the channel being movable relative to the fixation screw through a range of angles, the locking device including a first locking member for separately locking the channel against movement relative to the fixation screw and a second locking member for locking a rod against movement in the channel, 
 moving the channel relative to the fixation screw laterally relative to the spinal column toward the coronal plane of the spinal column to a first plane, 
 positioning a rod between the arm extensions and in the first plane, 
 moving the channel relative to the fixation screw medially relative to the spinal column toward the sagittal plane of the spinal column to place the rod in a second plane generally aligned with the sagittal plane, 
 rotating the locking device relative to the channel arm extensions to move the rod toward the base, 
 rotating the first locking member of the locking device relative to the channel arms to lock the channel relative to the fixation screw, 
 adjusting the rod relative to the channel, 
 rotating the second locking member of the locking device relative to the channel arms to lock the rod against movement relative to the channel, and 
 removing the channel arm extensions from the channel arms. 
 
     
     
       19. The method of  claim 18 , wherein the first locking member of the locking device is a screw having an external thread for engaging a thread on internal faces of the channel arms, the first locking member having a threaded bore, and wherein the second locking member of the locking device is a screw having an external thread for engaging the threaded bore of the first locking member. 
     
     
       20. The method of  claim 18 , wherein each of the channel arm extensions is connected to one of the channel arms at a line of weakness which promotes separation of the channel arm extension from its channel arm.